Is $15,000 to apply professional sealant to marble slabs a fair price?

I am remodeling my kitchen and found some gorgeous polished Calacatta Borghini slabs. I have a large kitchen and will need 4 slabs, which will also cover a 7 ft. long primary vanity. I am already paying over $60,000 for the slabs. I prefer the honed look, but my designer pushed these slabs and said it was no big deal to hone them. The $5,000 for honing is a significant amount that I could spend elsewhere in my remodel. My designer was very enthusiastic about these slabs, stating they were exceptional and that she had another client who would buy them if I didn't. These are exceptional Calacatta Borghini slabs at $250 per sqft. from one of the top stone dealers in the Bay Area. I looked for quite a while to find a sequence of 4 slabs of this type of marble with exquisite veining and consistent coverage, which is harder to find than one would think. I save the shine for some of the hardware. I'm learning now that with the amount of sanding that happens in the sealing process, the end result is less than a full polished look anyway, so I may not have to hone after all. When it comes to white marble, the sealant seems like a good idea.